Coupler

ABSTRACT

Couplers for attaching an accessory to an excavator arm of an excavator. Couplers having a first side for attaching the coupler to the excavator arm and a second side onto which the accessory will be coupled. The coupler includes a latch for selectively securing and releasing an attachment pin of the accessory in a jaw, groove, hook or slot in the second side of the coupler. The coupler is fully controllable from within the cab of the excavator and it allows improved security in the securement of the accessory to the coupler, i.e. preventing accidental decouplings, but while still allowing intentional decoupling operations to be carried out without undue burden.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Application No. 13/156,062filed Jun. 8, 2011, now U.S. Pat. No. 8,256,148 issued on Sep. 14, 2012;which is a continuation of U.S. application Ser. No. 12/439,785 filedDec. 15, 2009, now U.S. Pat. No. 7,984,576 issued on Jul. 26, 2011, asNational State 35 U.S.C. §371 filing of International Application No.PCT/GB2007/003324 filed on Sep. 4, 2007 claiming priority from bothUnited Kingdom Patent Application Nos. GB0711428.3 filed Jun. 13, 2007and GB0617394.2 filed Sep. 4, 2006. The entire contents of thepredecessor applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

In brief, however, the present invention relates couplers for attachingan accessory, such as an excavator bucket, to an excavator arm of anexcavator. Generally a coupler will comprise one or two jaws (orgrooves, hooks or slots) and one or two latches for selectively securing(or releasing) one or two attachment pins of the accessory in the oreach jaw (or groove, hook or slot).

BRIEF SUMMARY OF THE INVENTION

Many couplers have been developed in the art. Some are fully automatic,i.e. fully operable from within the cab of the excavator for bothcoupling and decoupling an accessory to or from the coupler and some arepart automatic/part manual, requiring many or most operations forcoupling and decoupling of an accessory to or from the coupler to becarried out from within the cab, but with one or more operations needingto be done instead at the coupler itself.

A part automatic and part manual coupler is disclosed in GB2359062. Thecoupler is attached remotely to the accessory, Le. from within the cabof the excavator. However, that attachment is made more secure by anadditional manual step—the insertion of a safety pin into a positionbehind a pivoting latching hook of the coupler.

A fully automatic coupler is disclosed in GB2330570. It has a gravityoperated blocking bar that is designed to fall behind the rear latchinghook during normal use, whereby when the coupler is in use, andtherefore in a normal, in-use or upright, orientation, the latching hookis prevented from being retracted by the presence of the blocking barbehind the latching hook. To release the accessory, however, thatblocking bar is lifted from that blocking position either by a secondhydraulic ram (Le. one that is not connected to the latching hook) orsimply by inverting the coupler, Le. by moving the excavator arm andcoupler into either the crowd position or to a position curled above theexcavator arm (an unconventional position for an excavator arm toassume). In that inverted orientation, the blocking bar will fall awayfrom its blocking position to allow the latching hook for the rearattachment pin then to be retracted by the latching hook's own hydraulicram.

There are also many other couplers, either fully automatic or partautomatic and part manual. See, for example, the couplers disclosed inthe following publications: Australian Patent AU557890, German UtilityModel DE20119092U, European Patent Applications EP0405811 and EP1318242,GB Patent Application GB2332417, U.S. Pat. No. 5,692,325 and U.S. Pat.No. 6,132,131, and PCT Publication WO99/42670.

The majority of prior art couplers have a first (or top) half that isfor attaching the coupler to the excavator, and that attachment isgenerally to an excavator arm of the excavator. The coupler ofEP0405813, however, is instead for attaching a digger bucket to thefront end loader of the excavator. The couplers then have on the otheror opposite side of the coupler two attachment pin engaging jaws,grooves, hooks or slots, whereby an accessory having a pair ofattachment pins (such as an excavator bucket) can be attached to thatcoupler via the pair of attachment pins: one of the jaws, grooves, hooksor slots is for engaging a first or front attachment pin of theaccessory and the other jaw, groove, hook or slot is for engaging thesecond or rear attachment pin of the accessory.

Couplers are also known for attaching accessories that have only oneattachment pin. Those couplers have just one jaw, groove, hook or slot.Typically, however, the accessory then has the other jaw, groove, hookor slot for engaging a second attachment pin, which is insteadpositioned on the coupler.

Despite the existence of numerous designs of coupler, there is still anever increasing demand upon the industry for the provision of even moresecurity for fully automatic couplers, and for which couplers no manualsteps need to be carried out by the user on the coupler for completingthe securement or detachment of an accessory. A purpose for this driveis that it allows the user to remain within the safe environment of thecab of the excavator. This is important since accessories and couplersare typically quite large and heavy pieces of equipment, and thus theyare potentially dangerous when being manipulated by an excavator.

For couplers having a pair of jaws, one of the jaws usually facesdownwards, i.e. away from the first half of the coupler, and that jaw isusually referred to as the rear jaw—it is normally located, in use, thefurthest away from the cab, and excavator arms usually extend from arear of the excavator. Due to its position, and the way it faces in use,often that jaw is not visible from the cab. The other jaw, however,usually faces away from that rear jaw and towards the cab. It generallyis also rotated by approximately 90° relative to the rear jaw, i.e.instead of pointing downwards, it usually points forwards. It isusually, in use, nearer to the cab than the rear jaw and thus it isusually referred to as the front jaw.

In many such prior art couplers a pivoting or sliding latching hook orlatching plate is provided for the rear jaw for locking an attachmentpin within that jaw. Thus, to couple the accessory to the coupler, afirst or front attachment pin is first engaged into an open front jaw ofthe coupler, and the coupler is then rotated or manipulated relative tothe accessory to position the second attachment pin into the coupler'sopen rear jaw. Then the latching hook or latching plate is drivenrearwardly, for example by a hydraulic piston or a screwthread, to closethe rear jaw to lock the rear attachment pin within the rear jaw. Thatin turn locks the front attachment pin in the front jaw.

Such a securement of the accessory to the coupler is entirely secure,subject to there being no failure of the respective components of thecoupler. However, users of such couplers additionally demand back-upsafety mechanisms to be incorporated into those couplers to provideassurances that an accessory cannot accidentally be decoupled from acoupler, even if the drive mechanism for the latching hook or thelatching plate is accidentally retracted or in the event of a misuse ofthe coupler, or even in the event of a failure of a component of thecoupler or the accessory. Further, there is a drive towards making theback-up safety features both automatic to implement and visible fromwithin the cab. By being automatic, they cannot be omitted or forgottenby the user, and by being visible from the cab it is possible to assesstheir status from the cab, i.e. to carry out a remote visual check as towhether the safety features have adopted their correct back-up safetyposition for ensuring a backed-up securement between the coupler and theaccessory. Further, the demand is for such couplers that still allowfully automatic coupling and decoupling of the accessory from thecoupler.

It should also be observed that many prior art couplers have theprovision for accommodating different accessories, i.e. ones havingdifferent distances between their respective attachment pins. Thatallows accessories from different manufacturers, or from differentproduct ranges, to be accommodated by the coupler (it is commonplace fordifferent buckets and other accessories from different manufacturers tohave different distances between their pairs of attachment pins, i.e.different pin spacings). Prior art couplers generally achieve that bythe provision of either a screwthread drive system or a hydraulic rammounted between the two jaws, grooves, hooks or slots. The screwthreador a hydraulic ram can then move one or both of the jaws, grooves, hooksor slots relative to a frame of the coupler to accommodate the differentpin spacings. Generally speaking, however, just one of the jaws,grooves, hooks or slots is moved by the screwthread or hydraulic ram,and that one is most frequently the rear one (or the latch associatedtherewith).

The securement of the two attachment pins within the two jaws isgenerally by a relative separation of the two pin-engaging components.That securement of the two fixed attachment pins of the accessory withinthe two jaws of the coupler can be referred to as a primary securementsince it alone provides a securement of the accessory to the coupler.Such primary securement mechanisms are strong and thus are generallyreliable since it is most unlikely that a component of it, such aseither the screwthread or the hydraulic ram, or the hook or jawthemselves, will fail. That is because these items are all designed tomeet the demands of the usual environment of use for the coupler.Indeed, these items are often “over-engineered” to provide a significantoverload buffer). Despite that, however, it is usual to provide theabove mentioned back-up safety (or failsafe) mechanisms to prevent theaccessory from decoupling from the coupler in the unlikely event of sucha failure.

Such safety back-up mechanisms, as known in the art, include at a mostsimple level, just a cover for the actuation circuit (usually in the cabof the excavator). That prevents accidental access to the actuationswitches during use of the accessory. However, there is a demand foradditional security. As such, failsafe mechanisms are provided in or onthe coupler itself. See, for example, the coupler of EP1318242. It has aspring driven hook for the front jaw, which hook defaults to a closedstate for securing a front attachment pin within the front jaw of thecoupler. Therefore, even if the rear hook fails, the accessory issecured within the coupler. A problem with that coupler, however, isthat if the decoupling command is given accidentally, the spring drivenhook will automatically be retracted by the hydraulic ram as the slidingrear jaw reaches a fully retracted position. U.S. Pat. No. 6,132,131 andU.S. Pat. No. 5,692,325 similarly provide a latching hook for the frontjaw that is driven by the rear jaw's hydraulic ram, and as such theyalso have that same problem. In GB2332417, however, a toggling dual-hookarrangement is provided—there are two moving hooks that areinterconnected by a toggling arrangement to ensure that as one hookopens the other hook closes, and vice versa. This prevents both hooksfrom opening simultaneously. However, if either the link or one of thehooks fails, the coupling between the accessory and the coupler becomesvulnerable.

The present invention, therefore, seeks to provide coupler designs thatare both fully controllable from within the cab, and that will allowimproved security in the securement of the accessory to the coupler,i.e. preventing accidental decouplings, but while still allowingintentional decoupling operations to be carried out without undueburden.

According to a first aspect of the present invention there is provided acoupler for coupling an accessory to an excavator arm of an excavator,the coupler comprising a first portion for attaching the coupler to anexcavator arm of an excavator and the coupler having a second portionadapted to receive an accessory with two attachment pins, wherein:

the second portion has two jaws, one for receiving a first attachmentpin of an accessory and the other for receiving a second attachment pinof the accessory;

a first latch is associated with the first jaw for securing the firstattachment pin within the first jaw when the first latch is in alatching position;

a second latch is associated with the second jaw for securing the secondattachment pin within the second jaw when the second latch is in alatching position;

a third latch is provided that extends between the first and secondlatches, the third latch, when in a latching position, being adapted toresist movement of the first latch from a latching position into anon-latching position; and

when the third latch is in a non-latching position, the first latch isnot resisted from moving between a latching position and a non-latchingposition by the third latch.

Preferably the second latch is linked or connected to the third latch.

Preferably the second latch is pivotally linked to the third latch. Theymay, however, be an integrally formed member.

In another arrangement, the second and third latches are separatecomponents that are selectively engageable with each other by movementsof one or both of those latches, and wherein the third latch alsoresists movement of the second latch from a latching position into anon-latching position when it is itself in a latching position butwherein it will not resist movement of the second latch from a latchingposition into a non-latching position when it is in some otherpredetermined position. Preferably that predetermined position cannot beassumed by the third latch while a first attachment pin is securedwithin the first jaw by the first latch. Preferably that is achieved bythe provision of a flange on the first latch that restricts movement ofthe third latch while a first attachment pin is secured within the firstjaw by the first latch.

Preferably the latching position of the third latch is its defaultposition, i.e. the position it assumes during normal use of the coupler(i.e. non-inverted and with an attachment attached thereto).

Preferably the third latch is moveable from a latching position into anon-latching position by means of gravity by at least partiallyinverting the coupler. Alternatively, or additionally, a mechanicalactuator may be provided for moving the third latch.

A biasing member may be provided to bias the third latch towards alatching position.

Preferably the third latch, in a latching position bears against thefirst latch.

One or more of the latches may comprise a solid bar and/or a hook.

One or more of the latches may comprise a pair of solid bars and/orhooks.

One or more of the latches may comprise a bifurcated bar or hook.

Preferably the first latch is moveable from a latching position into anon-latching position by a mechanical actuator, such as a hydraulic ram.

Preferably the second latch is moveable from a latching position for thesecond jaw into a non-latching position for the second jaw by means ofgravity by at least partially inverting the coupler. Alternatively, oradditionally, a mechanical actuator may be provided for moving thesecond latch.

A biasing member may be provided to bias the second latch towards alatching position.

The same biasing member and/or mechanical actuator may control themovements of both the second latch and the third latch since thoselatches are linked or connected together.

Preferably the second jaw has a recessed groove in its lower half.

Preferably the coupler can accommodate a range of pin spacings betweenthe two attachment pins of the accessory by making the rear jawsignificantly wider in side view than the front jaw (or wider than thediameter of a typical rear attachment pin for that size of coupler). Inthis manner, accessories from different manufacturers, with differentpin spacings, can be attached to the coupler without modification ofeither the coupler or the accessory.

For adjusting the first latch, the mechanical actuator is preferably ahydraulic ram. It might, however, be a pneumatic ram or a screwthreaddrive mechanism.

Preferably the mechanical actuator is mounted within the confines of thecoupler, generally between and slightly above the two jaws.

Preferably the first latch is a pivoting latching hook, or a pair ofpivoting latching hooks.

Preferably the first latch pivots to move through an arc between alatching position and a non-latching position. In other embodiments itmight be a plate that slides such that it moves linearly between alatching position and a non latching position.

Each jaw may be bifurcated. It is preferred, however, that the first jawis a pair of jaws formed in the two sidewalls of the coupler. It is alsopreferred that the second jaw is a single piece jaw, for example amoulded jaw or a welded multi-part fabrication.

It should be noted that the term “jaw” should be interpreted toencompass similar attachment pin receiving members such as grooves,hooks or slots, or other similar terms that are to be found in the art.For example, a hook, a groove or a slot in the main body of a couplercan form a jaw.

Preferably the first latch has a latching face facing in a firstdirection for bearing against the first attachment pin and a second facefacing away from that latching face. Preferably one or more flange isformed on that second face. Then, in its latching position, the thirdlatch preferably rests on one or more of those flanges. Preferably thepredetermined position lies beyond the position that the third latchassumes when resting upon that flange.

The end of the third latch adapted to rest on those flanges may have oneor more stepped surfaces. It would be one or more of those steppedsurfaces that would preferably rest on that or those flange(s).

The first latch is adapted to be moveable into a non-latching positionfrom a latching position by retracting it generally in the directionthat its second face faces. However, when a pin is not within the firstjaw, the first latch is also able to move in the opposite directionbeyond the position in which its latching face would have engaged anattachment pin had one been in the first jaw. By that additional rangeof motion, the flange or flanges on the first latch can be moved clearof the reach of the third latch. As a result the range of availablemotion for the third latch is also extended. That enables the thirdlatch to be extended into the predetermined position, if desired.

The present invention also provides a method of attaching an accessoryto a coupler on an excavator arm of an excavator, the method comprising:

a) providing an excavator with a powered excavator arm having a coupleron an end thereof, the coupler comprising two jaws and a latch for eachjaw, one of the latches being powered for movement between a latchingposition and a non-latching position, and the other being moveable froma latching position into a non-latching position by fully extending thepowered latch beyond a latching position, i.e. while there is no pinwithin that jaw, into a fully extended position while the coupler is ina normal, in use, orientation;

b) providing an accessory with two accessory pins thereon sized andspaced to fit into the two jaws of the coupler;

c) powering the powered latch to extend it into the fully extendedposition to move the other latch into a non-latching position;

d) manipulating the coupler to locate a first attachment pin of theaccessory into the jaw associated with that other latch;

e) curling the accessory and coupler, using the excavator arm, so as toinvert the coupler, thereby placing the accessory roughly above thecoupler;

f) reverse powering the powered latch to retract the powered latch foropening its associated jaw, whereupon the second attachment pin locatesinto that jaw under the weight of the accessory;

g) powering the powered latch to extend it to a latching position forsecuring the second attachment pin in its jaw; and

h) uncurling the coupler, using the excavator arm. The attachment is nowattached securely to the coupler.

In an alternative arrangement, the present invention provides a methodof attaching an accessory to a coupler on an excavator arm of anexcavator, the method comprising:

a) providing an excavator with a powered excavator arm having a coupleron an end thereof, the coupler comprising two jaws and a latch for eachjaw, each latch being selectively moveable between a latching positionand a non-latching position, wherein one of the latches is powered formovement between a latching position and a non-latching position, andthe other is selectively resisted from movement from a latching positioninto a non-latching position by a third latch, wherein that third latchcan be moved into a predetermined, non-latch-resisting position uponextending the powered latch beyond a latching position, i.e. while thereis no pin within that jaw, into a fully extended position while thecoupler is in a normal, in use, orientation,

b) providing an accessory with two accessory pins thereon sized andspaced to fit into the two jaws of the coupler;

c) powering the powered latch to extend it into the fully extendedposition for moving the third latch into its predetermined,non-latch-resisting position;

d) manipulating the coupler to locate a first attachment pin of theaccessory into the jaw associated with the other latch;

e) curling the accessory and coupler, using the excavator arm, so as toinvert the coupler, thereby placing the accessory roughly above thecoupler;

f) reverse powering the powered latch to retract the powered latch foropening its associated jaw, whereupon the second attachment pin locatesinto that jaw under the weight of the accessory;

g) powering the powered latch to extend it to a latching position forsecuring the second attachment pin in its jaw; and

h) uncurling the coupler, using the excavator arm. The attachment is nowattached securely to the coupler.

The present invention also provides a method of detaching an accessoryfrom a coupler on an excavator arm of an excavator, the methodcomprising:

a) providing an excavator with a powered excavator arm having a coupleron an end thereof and with an accessory coupled thereto, the accessoryhaving two accessory pins thereon located within two jaws of thecoupler, and secured into those jaws by respective latches associatedwith each jaw, wherein one of the latches is powered for movementbetween a latching position and a non-latching position, and the otherlatch is moveable from a latching position into a non-latching position,when an attachment pin is not located within the other jaw, by fullyextending the powered latch beyond a latching position into a fullyextended position while the coupler is in a normal, in use, orientation;

b) curling the accessory and coupler, using the excavator arm, so as toinvert the coupler, thereby placing the accessory roughly above thecoupler;

c) reverse powering the powered latch to retract the latch for openingits associated jaw;

d) uncurling the coupler and attachment, using the excavator arm, toposition the accessory below the coupler whereupon the attachment pinwithin the opened jaw exits the opened jaw under the weight of theaccessory;

e) powering the powered latch to extend it into the fully extendedposition to move the other latch into a non-latching position to openthe other jaw; and

f) manipulating the coupler relative to the attachment to remove theother attachment pin of the accessory from that other jaw.

Preferably the act of inverting the coupler and accessory to place theaccessory roughly above the coupler serves to move a mechanical stopaway from a latching position behind the powered latch.

Preferably the mechanical stop is linked to the other latch.

Preferably the movement of that powered latch into the fully extendedposition allows the mechanical stop to move beyond its own latchingposition into a final release position, or the above mentionedpredetermined position, whereupon the other latch is released to be freeto move into a non-latching position.

In an alternative arrangement, the present invention provides a methodof detaching an accessory from a coupler on an excavator arm of anexcavator, the method comprising:

a) providing an excavator with a powered excavator arm having a coupleron an end thereof and with an accessory coupled thereto, the accessoryhaving two accessory pins thereon located within two jaws of thecoupler, and secured into those jaws by respective latches associatedwith each jaw, each latch being selectively moveable between a latchingposition and a non-latching position, wherein one of the latches ispowered for movement between a latching position and a non-latchingposition, and the other latch is selectively resisted from movement froma latching position into a non-latching position by a third latch,wherein that third latch can be moved into a predetermined,non-latch-resisting position upon extending the powered latch beyond alatching position, i.e. while there is no pin within that jaw, into afully extended position while the coupler is in a normal, in use,orientation;

b) curling the accessory and coupler, using the excavator arm, so as toinvert the coupler, thereby placing the accessory roughly above thecoupler;

c) reverse powering the powered latch to retract the latch for openingits associated jaw;

d) uncurling the coupler and attachment, using the excavator arm, toposition the accessory below the coupler whereupon the attachment pinwithin the opened jaw exits the opened jaw under the weight of theaccessory;

e) powering the powered latch to extend it into the fully extendedposition to move the third latch into its predetermined,non-latch-resisting position;

f) moving the other latch into a non-latching position; and

g) manipulating the coupler relative to the attachment to remove theother attachment pin of the accessory from that other jaw.

Preferably step f) is achieved by recurling the accessory and coupler,using the excavator arm, so as partially to invert the coupler, therebyplacing the accessory in a position that is substantially level with thecoupler. That then allows the other latch to fall into a non-latchingposition under the influence of gravity if it is free to do so. Itshould be appreciated, however, that that other latch might instead bepower operated, e.g. it may have its own actuator, such as a hydraulicram.

It would also be desirable to provide just a simple supplementaryfailsafe or securement mechanism for couplers. Preferably thesupplementary failsafe or securement mechanism will be able to ensurethat an accessory will still be retained upon the coupler until thatsupplementary failsafe or securement mechanism is released even in theevent of a catastrophic failure of the primary securement mechanism,e.g. the hydraulic ram or the screwthread, or even a moveable jaw,groove, hook or slot, or even in the event of an accidental orinadvertent release of that primary securement mechanism by theoperator.

According to a further aspect of the present invention, therefore, thereis provided a coupler for coupling an accessory to an excavator arm ofan excavator, the accessory comprising at least one attachment pin foruse in the coupling, the coupler comprising a first side for attachingthe coupler to an excavator arm of an excavator and the coupler having asecond side onto which the accessory will be coupled, the second sidecomprising a jaw for receiving the attachment pin of the accessory forconnecting the accessory to the coupler by the engagement of the jawwith the attachment pin, wherein the jaw comprises a gravity-operatedmember having a first state—the jaw-open or jaw-unlocked state, and asecond state—the jaw-closed or jaw-locked state, the gravity-operatedmember at least partially closing the jaw of the coupler when it is inits first state, said first state being achieved by the gravity-operatedmember when the coupler (and, when connected, the accessory) is in anormal, in-use orientation due to the influence of gravity on thegravity-operated member.

Preferably the two different states of the gravity-operated member aretwo different positions of the gravity-operated member. However, thegravity-operated member might instead simply remain in a constant normalposition, instead switching between a rotatable or free state and anon-rotatable or more restricted state depending upon the orientation ofthe coupler.

The present invention, with its gravity-operated member, therefore has ajaw that can be selectively opened or closed (or unlocked and locked)dependent upon the orientation of the coupler since gravity will open orunlock the member in one orientation and will close or lock the member(with the jaw at least partially closed by the member) in otherorientations.

It should be noted that the terms “jaw” should be interpreted toencompass similar pin receiving members such as grooves, hooks or slots,or other similar terms that are to be found in the art. For example, ahook can form a jaw, a groove or a slot, and similarly a groove is inessence just a slot. In view of that, and also for the sake ofconvenience, the single term “jaw” is used hereinafter.

Preferably, in a first orientation (e.g. the normal, in-use orientation)the member will fall under the influence of gravity into its closedposition. However, upon reorienting the coupler, for example to aninverted position, the member will fall under the influence of gravityfrom that closed position into its open position. Instead of simplyfalling between two positions, however, the member may roll, slide orpivot between those positions. Alternatively, it might remainstationary, instead either being locked or unlocked from a particularclosed position dependent upon the orientation (or path of motionbetween orientations) of the coupler.

When open (or unlocked), an attachment pin within the jaw, when nototherwise restrained, can be removed from the jaw. Similarly, anattachment pin can be inserted into the jaw. However, when closed, bethat either completely or partially, or when locked, an attachment pinwithin the jaw cannot be removed from the jaw since the locked or closedmember will block its path out of the jaw. It might be possible,however, dependent upon the chosen configuration of the locking/closingmechanism, to insert an attachment pin into the jaw even when thegravity-operated member is either closing the jaw or locking the jawclosed, e.g. by sliding it sideways into the jaw, rather than from thefront of the jaw.

Preferably, the gravity-operated member is mounted onto the second sideof the coupler either directly to the jaw, or onto a frame of thecoupler, which frame carries the jaw.

Preferably the gravity-operated member is a pivotal member, mounted tothe coupler about a pivot axis, the pivoting of the member moving itbetween its open and closed (or locked and unlocked) positions.

Preferably the first side is a top side of the coupler, the second sideis a bottom side of the coupler, and the coupler also comprises a framehaving two sideplates extending generally between the top and bottomsides of the coupler. Preferably the pivot axis runs perpendicular tothose sideplates, i.e. in a transverse direction of the coupler. Theaxis might, however, extend in a longitudinal direction of the coupler(the above-mentioned pin-spacing is measured in the longitudinaldirection of the coupler, whereas the attachment pins of an accessoryextend in the transverse direction of the coupler).

The gravity operated member might comprise two pivoting axes, the firstrunning in the transverse direction of the coupler and the secondrunning in the longitudinal direction of the coupler. This allows themember to pivot in more than one direction. Even more pivotingdirections can be achieved with a ball and socket joint.

Instead of pivoting, the member may slide or roll between its open andclosed/locked and unlocked positions.

Preferably an accessory for coupling to the coupler comprises twoattachment pins, the coupler thereby needing two jaws. One or moregravity-operated member as defined above may be provided for each oreither jaw. However, preferably only one jaw has a gravity-operatedmember for closing the jaw, and most preferably it will just be thefront jaw—usually the jaw without a hydraulically or mechanically drivenlatching hook or latching plate.

Preferably the other jaw (the rear jaw) points downwards and has ahydraulically or mechanically driven latching hook or latching plate,which, together with the first jaw, (which usually points forwards)provides a primary coupling mechanism for coupling the accessory to thecoupler in a fixed orientation relative to the coupler. Thegravity-operated member is then preferably a secondary securingmechanism (as a secondary securing mechanism, the gravity-operatedmember does not serve to couple the accessory to the coupler in a fixedorientation relative to the coupler, but instead merely serves to attachor tether the accessory to the coupler simply by retaining theattachment pin within the first jaw when the member is in its closed orlocked position).

The coupler with two jaws may be in accordance with any of the otheraspects of the invention described above.

Preferably, the gravity-operated member is not hook-shaped. The memberinstead is preferably a blocking bar, a blocking toggle or a blockingwedge.

By the term “gravity-operated”, it is intended that no spring orhydraulic member, or any other mechanical, hydraulic, magnetic orelectrical biasing influence, is to be used, in normal use, to move themember from its closed or locked position into its open or unlockedposition. Instead, simply gravity is to be relied upon for that purpose,whereby the coupler has to be at least partially inverted in order torelease the gravity-operated member. Such an inversion of the coupler,sufficient for decoupling the accessory from the coupler, should notoccur during the normal use of the coupler with an accessory attachedthereto since it is unusual to operate an excavator arm and accessory ina manner that places the accessory suitably above the end of theexcavator arm.

Similarly it is desired just to rely upon gravity to return the memberto its closed or locked position. However, it is possible to provide agravity-operated member that has a biasing member, such a spring, forassisting in ensuring that the gravity-operated member will fall, moveinto or assume its closed or locked state when the coupler is in itsnormal, in-use orientation. In such an embodiment, gravity would stillbe relied upon to overcome that biasing force in order for the member toassume its open or unlocked state.

Preferably, when the coupler comprises two jaws, the second or rear jawis associated with a moveable latch and a mechanical stop forselectively locating behind that moveable latch for selectivelyrestricting the movement of that moveable latch.

Preferably the mechanical stop is also operable under the influence ofgravity.

Preferably, when the coupler is in a normal, in use, level orientation,i.e. with the two jaws approximately level with each other, with anaccessory arranged below the coupler, and with an attachment pin of theaccessory retained within the second jaw by the moveable latch, themechanical stop tends, under the influence of gravity, to fall into aposition resting against the moveable latch for restricting the movementof that moveable latch from that pin latching position.

Preferably, when the coupler is in an inverted position, the mechanicalstop instead falls away from the moveable latch, into a non-latchingposition. That position allows the second latch to be retracted from itslatching position for releasing the pin retained by it within the secondjaw.

Preferably the mechanical stop, when it is resting against the moveablelatch provided for the rear jaw, also provides a movement-restrictingfunction for the gravity operated member, whereby the gravity operatedmember cannot be moved into a jaw-open position.

Preferably the mechanical stop, when the coupler is inverted, alsoprovides against the gravity operated member a bias towards afront-jaw-closing position for that gravity operated member.

Preferably the mechanical stop has a third position that is onlyachievable by the mechanical stop while an attachment pin is notretained within the second jaw. Preferably that position is a positionbeyond the position assumed by the mechanical stop as it rests againstthe moveable latch for the rear jaw. Preferably that third positiondisengages the movement-restricting function of the mechanical stop inrelation to the gravity operated member. Thus, while an attachment pinis secured within the rear jaw by the moveable latch associatedtherewith, the front jaw cannot be opened by movement of the gravityoperated member. However, upon disengagement of the attachment pin fromthe rear jaw, the third position for the mechanical stop can beachieved, and thus the front jaw can also be opened.

Preferably the mechanical stop has a pivot axis and a first arm pointingfrom that pivot axis generally towards the gravity operated member forthe front jaw, and a second arm pointing from that pivot axis generallytowards the moveable latch for the rear jaw.

Preferably the two arms extend away from each other at an angle ofgreater than 90° (and less than 270°).

Preferably the arm that points generally towards the gravity operatedmember has a flange on it that is adapted to bear against acorresponding flange of the gravity operated member. The interactionbetween those flanges restrict the motion of the gravity operatedmember. Thus, when the mechanical stop is in its third position, the twoflanges are separated with respect to each other such that they cannotbear against each other through the range of motion required by thegravity operated member for opening the front jaw.

Preferably the two flanges have opposing angled faces that bear againsteach other when the coupler is inverted for biasing the gravity operatedmember into or towards a locked or closed position.

For a pivoting mechanical stop that operates under the influence ofgravity, the moment of inertia for the mechanical stop needs to be suchthat arm of the blocking bar extending towards the moveable latch forthe rear jaw will tend to overbalance the other arm. For example, thearm of the blocking bar extending towards the moveable latch will tendto be significantly heavier or longer than the other arm.

Preferably the gravity operated member has a stop-surface adapted tobear against a corresponding surface of the coupler's frame when thegravity operated member is in a front-jaw-locking or closing positionfor preventing movement of the gravity operated member beyond thatfront-jaw-locking or closing position. Two such stop surfaces that arespaced apart may be provided to spread the loading across a larger areaof the frame in the event of the accessory's weight being carried bythat gravity operated member, e.g. if the accessory is incorrectlymounted onto the coupler.

Preferably the two stop surfaces are planar. More preferably they arenot co-planar.

Preferably one of the stop surfaces is a forward facing surface, withthe corresponding surface of the coupler's frame lying as a rearwardfacing surface of the frame, for example on a forwardly extendingintegral rail of the frame.

Preferably the second stop surface is provided on an underside of athird flange of the gravity operated member.

Preferably, the gravity-operated member is arranged such that it will bein its locked or closed state for most normal, in-use orientations androtations of the coupler. Those normal, in-use orientations will usuallyrange from a level orientation (i.e. where the two attachment pins arelevel) to perhaps at least 45° from that level orientation in a first ordigging curl direction (i.e. moving towards the crowd position) and fromthe level orientation to perhaps at least 135° from that levelorientation in an opposite curl direction—the emptying curl direction(i.e. up and over the excavator arm). Therefore the preferred embodimentof the present invention will keep its gravity-operated member in alocked or closed position through a range of angles of curl perhaps inexcess of 180°.

In a more preferred embodiment, the member will only move to its openposition in response to specific re-orientations of the coupler, such asa full inversion of the coupler (i.e. into a position curled up andabove the excavator arm, which may be a rotation of more than 1700 inthe emptying curl direction from the level orientation), or in responseto lesser rotation, e.g. 600 or more in the digging curl direction (i.e.into or towards the crowd position). Adjusting the position of the pivotpoint of the member relative to the centre of gravity of the memberprovides for different angle ranges in that regard where the pivot axisruns transverse across the coupler, e.g. between sideplates of thecoupler. Further, undesired rotations for the member can be avoided, orrotation limits can be provided, by pivot stops.

It should also be noted that the former of the two decoupling positions(i.e. a position curled up and above the excavator arm) is the lessdesirable position for the coupler during a decoupling of the accessoryfrom the coupler. That is because it positions the coupler at asignificantly more elevated position than that achieved in the crowdposition. As a result, such a position would never be used in practice.It should also be noted that such a position serves no useful purpose,and thus is an unlikely position for an operator to put the couplerinto.

It is also preferred that a decoupling of the accessory from the coupleris not an automatic result of a single act of (at least partially)inverting the coupler. With the preferred embodiment of the presentinvention, there is also a primary coupling mechanism, with the gravityoperated member providing just a secondary securement function, forexample of being an automatic tether. As a result, the merereorientation of the coupler into a position that moves thegravity-operated member into an open or unlocked position will notactually decouple the accessory from the coupler. The primary couplingmechanism would also need to be disengaged or retracted before thatcould happen.

It should also be noted that when a coupler is in a fully invertedorientation (i.e. up above the excavator arm, and rotated by more than1700 from the level orientation), the weight of the accessory will bebearing directly down onto the coupler. The weight of the accessory,therefore, should keep the accessory on the coupler.

The accessory also cannot be released while the weight of the accessoryis forcing the attachment pin to press into the back of the jaw. That,therefore, is a preferred state for the coupler at the time ofdecoupling. That state is achieved for example by reorienting thecoupler into the crowd position. Then, to withdraw the attachment pinfrom the jaw in that orientation, the weight of the accessory will berested on the floor or the like, preferably in a stable manner (e.g. ona flat bottom surface of the accessory or on a stand for the accessory),and then the weight of the accessory on the ground is used to keep theaccessory stationary while the jaw is disengaged from the attachment pinof the accessory by manipulation of the excavator arm and the couplerrelative to that accessory in an appropriate manner (after disengagementof any primary coupling mechanism).

The present invention therefore allows the decoupling of an accessoryfrom the coupler by the use of specific and deliberate reorientationsand manipulations, which acts would not be carried out during normalexcavation operations. As a result, the accessory cannot be decoupledfrom the coupler accidentally. Thus the present invention will provideremarkable reassurances to an excavator operator.

The present invention also provides various methods of coupling anaccessory onto a coupler that is attached to an excavator arm of anexcavator.

The present invention also provides various methods of uncoupling anaccessory from a coupler that is attached to an excavator arm of anexcavator.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

These and other preferred features and embodiments of the presentinvention will now be described purely by way of example with referenceto the accompanying drawings in which:

FIG. 1 is a cut-away side elevation of a preferred embodiment of thepresent invention;

FIG. 2 is a schematic cut-away perspective of a preferred embodiment ofthe invention with two attachment pins of a bucket (part illustrated)secured within the two jaws of the coupler;

FIGS. 3 to 8 are schematic cut-away perspectives of the embodiment ofFIG. 2 illustrating the preferred sequence of operations for firstlyattaching an attachment to the coupler (FIGS and. 3 to 5 and then fordisengaging the attachment from the coupler (FIGS. 6 to 8);

FIG. 9 is a top perspective view of the preferred coupler, with anattached bucket (in part) illustrating the preferred elements of thecoupler roughly in plan.

FIG. 10 shows a part sectional side elevation view of a couplerillustrating a further embodiment of the present invention;

FIG. 11 shows the same part sectional/side elevation view of the couplerof FIG. 10, but in which the member is in its second, jaw-closedposition;

FIG. 12 shows a front elevation view of the coupler of FIGS. 10 and 11with the member in its jaw-closed position;

FIG. 13 is a detail side view of the gravity-operated member of FIGS.10, 11 and 12;

FIG. 14 is a front perspective view of a further embodiment of thepresent invention;

FIG. 15 is a schematic view of the embodiment of FIG. 14 showing anattachment pin of an accessory passing the member;

FIG. 16 is a front elevation view of the embodiment of FIG. 14 with themember in its jaw-closed position;

FIG. 17 is a side elevational view of a further coupler in accordancewith the present invention;

FIG. 18 shows the internal working mechanisms of the coupler of FIG. 17;

FIG. 19 is a schematic view of the coupler of FIG. 17 with twoattachment pins of an accessory secured thereto;

FIGS. 20 to 23 schematically illustrate the operational steps involvedfor attaching an accessory to the coupler of FIG. 17;

FIGS. 24 and 25 show the coupler of FIG. 17, rotated by 45° fromhorizontal, for illustrating the movement restricting function of themechanical stop for the gravity operated member;

FIGS. 26 to 30 schematically illustrate the operational steps involvedfor disengagement of an accessory from the coupler of FIG. 17; and

FIGS. 31, 32 and 33 show details of the interactions between the gravityoperated member and the frame of the coupler.

DETAILED DESCRIPTION OF THE INVENTION

Referring first of all to FIG. 1, a cut-away side elevation of apreferred coupler 10, showing the preferred internal working mechanismsfor the coupler 10 of the present invention, is shown. The coupler 10has a first, or upper, portion 12 and a second, or lower, portion 14.The coupler also has a front 16 and a rear 18. In normal use the front16 points towards the cab of an excavator (not shown), whereas the rear18 points away from the cab.

The upper portion 12 is adapted for connecting the coupler 10 onto theexcavator arm of the excavator and it is displaced slightly forwardlyrelative to the lower portion 14, as is conventional. In thisillustrated embodiment, however, it is displaced further forward thanwould be conventional. That, however, is optional.

In the upper portion 12, two pairs of holes 20 are provided, althoughonly one of each pair is shown. Those holes 20 are for attachment of thecoupler 10 to the excavator arm of the excavator by using a pair ofattachment pins. That attachment is conventional in the art, and thusneeds no further discussion.

The lower portion 14, which is instead for coupling onto an accessory,such as an excavator bucket, instead uses a pair of jaws for thatattachment. The first jaw, or the rear jaw 22, and the second jaw, orthe front jaw 24, conventional as well for that purpose, and thus aresized to receive a further pair of attachment pins, this time fitted tothe accessory.

As is conventional now, the rear jaw 22 is a downwardly facing jawwhereas the front jaw 24 is a forward facing jaw. Thus, with thisarrangement, the basic principle behind coupling an accessory to thecoupler is first to locate a front attachment pin of the accessorywithin the front jaw 24 and then to swing a rear attachment pin of theaccessory into the rear jaw from below. Next, to prevent that second pinfrom just swinging out of the rear jaw, a pivoting latching hook, orfirst latch 26, is associated with that rear jaw 22 such that it can beswung about a pivot 28 into a latching position across the rear jaw 22to secure the second attachment pin within the rear jaw 22. That thensecures the accessory firmly onto the coupler 10.

As is also conventional, in this preferred embodiment the pivotinglatching hook 26 is driven into that latching position by a mechanicalactuator such as a hydraulic ram 32.

However, instead of a hydraulic ram, a pneumatic ram or a screwthreaddrive, or some other drive device, might be provided.

Further, instead of a pivoting latching hook, a sliding mechanism forthat latch might 5 instead be provided.

The present invention is distinguished over prior art couplers, however,by the provision of a unique second latch 34, and an attached thirdlatch, or mechanical stop 36. They are provided to interfere with theabove basic principle of operation of the coupler so as to preventinadvertent, or non-deliberate, disengagement of the accessory from thecoupler 10, while still allowing deliberate disengagement of theaccessory from the coupler.

The second latch 34 is associated with the front jaw 24 and it isadapted selectively to close the front jaw 24 for securing an attachmentpin within the front jaw 24. Because of that latch 34, before theaccessory can be decoupled from the coupler 10, steps have to be takento cause that latch to retract for opening the front jaw 24. Furtherdetails of those steps, and the more specific details of that secondlatch, will now be described in further detail with reference to FIGS. 2to 8.

As can be seen in FIG. 2, which shows only one half of the second latch34, the second latch 34 is a pivotal plate connected via a hinge to athird element 36. The plate is generally rectangular with a solidsection and is preferably made from steel. Its hinge has a central axis42.

The second latch 34 can drop in and out of a latching position withinthe front jaw 24 by sliding generally linearly through a slot defined bytwo plates 48, 50. It can keeps a generally linear line of movementsince it can pivot about its own pivot axis 42, i.e. relative to thethird element 36. Further, its interaction with the two plates 48, 50within that slot defined therebetween, prevents rotation of the secondlatch 34 relative to main body of the coupler 10, and relative to thefront jaw 24.

In an alternative construction, however, the second latch 34 and themechanical stop 36 may be a single unitary element, thus not needing atleast the front plate 48 of the two plates 48, 50.

The third element 36 is a mechanical stop 36. As more clearly shown inFIG. 3, in which the hydraulic ram 32 has been removed for clarity, themechanical stop 36 is itself also a pivotal member—it is pivotallymounted relative to the main body 38 of the coupler 10 about a pivot pin(not shown) via a bearing hole 40 in the mechanical stop 36. Thus themechanical stop 36 can pivot relative to the main body 38 of the coupler10.

The mechanical stop 36 has a first arm with an end 56 that extends awayfrom the bearing hole 40 away from the second latch 34. It also has asecond arm extending away from the bearing hole 40, but instead towardsthe second latch 34. That second arm carries the pivot axis 42 for thesecond latch 34 near its end and that axis is located directly above, orin line with, the slot defined between the two plates 48, 50 of thefront jaw.

As a result of that geometry (of the mechanical stop relative to theaxes and the slot of the front jaw), it is through the pivoting motionof the mechanical stop 36 about the central axis of its bearing hole 40,i.e. relative to the main body of the coupler, that the second latch 34can be lifted or lowered generally linearly through the slot between thetwo plates 48, 50.

The pivotal movement of the mechanical stop 36 is illustrated by thearrows 44 in FIG. 3.

The generally linear motion of the second latch 34 relative to the frontjaw 24 is illustrated by the double headed arrow 46 also in FIG. 3.

It is preferred that the first arm of the mechanical stop, i.e. the armextending from the bearing hole 40 to the end 56, is at least twice aslong as the second arm of the mechanical stop 36, i.e. the arm extendingfrom the bearing hole 40 towards the second latch 34. Similarly it ispreferred that that first arm of the mechanical stop is at least twiceas long as the second latch 34. Those arrangements together should allowthe second arm to have a greater moment of inertia about the bearinghole 40 than the second arm combined with the second latch 34.Similarly, or alternatively, the first arm may simply be sufficientlyheavier than the second arm and second latch combined to provide thedesired greater moment of inertia for that first arm about the bearinghole 40 than the second arm and second latch 34 combined. This moment ofinertia arrangement is desired so that gravity can always cause thefirst arm to drop and the second arm to lift, whenever the orientationof front and rear of the coupler is altered with respect to one another.This is the desired arrangement despite the fact that that arrangementtends to cause the second latch 34 to be permanently biased towards anon-latching position when the coupler 10 is in a normal useorientation, i.e. with the attachment being located underneath thecoupler. That is because in normal use the second latch 34 will not beable to lift fully up into the roof of the front jaw 24 for opening thefront jaw 24 due to the first latch 26 interfering with the range ofmotion available to the mechanical stop 36. Instead, the second latch'snormal position during use is as shown in FIG. 2—it extends partiallyacross the opening of the front jaw 24. That is sufficient for “closing”the second jaw for locking an attachment pin within the second jaw. Thisfeature is further explained below with regard to attaching anddetaching an accessory to and from the coupler.

Returning, however, to the design of the second latch 34, in preferredembodiments the second latch 34 is painted in a high visibility coloursuch as orange or red. That is preferred since the second latch is oneof the safety features of the coupler that will nearly always be visiblefrom the cab of the excavator—it at least partially extends across theopening of the front jaw 24, and that opening generally faces towardsthe cab during normal use of accessories. The high visibility secondlatch 34, therefore, acts as a visible marker for confirming the corrector secure attachment of an accessory to the coupler 10, and that visualaid can be seen by the excavator operator from the within his cab.

For securing the rear attachment pin 54 within the rear jaw 22, however,this preferred embodiment has a first latch 26 in the form of a pivotinglatching hook. That pivoting latching hook is mounted for rotation abouta pivot pin 28 and is moveable between a latching position and anon-latching position by a hydraulic ram 32. That hydraulic ram 32 isthe primary mechanism for holding that first latch 26 in its latchingposition. To assist with that and to add to the security of that, it ispreferred that the hydraulic ram is provided with a check valve toprevent a release of the hydraulic pressure on the ram in the event of ahydraulic failure such as a cut in the hydraulic piping leading to it.

The mechanical stop 36, however, provides a further backup to preventthe inadvertent or non-deliberate release or retraction of the firstlatch 26 into a non-latching position. To that end the mechanical stop36 provides an interference function against that first latch 26, asmost clearly illustrated in FIG. 5.

For providing that interference function, the first arm of themechanical stop 36 extends away from the bearing hole 40, and away fromthe second latch 34, towards the first latch 26. Further its length islong enough to bear against the first latch 26 when the first latch isin a latching position against an attachment pin. However, the first armis not too long—it needs to be able to swing past the first latch 26when the first latch 26 is fully extended, i.e. when there isn't anattachment pin within the rear jaw.

Because of the mechanical stop 36, i.e. when the first latch is in alatching position against an attachment pin, the first latch 26 cannotbe retracted even by the hydraulic ram 32 until that mechanical stop 36has been moved from that interference position.

The movement of that mechanical stop 36 is achieved by inverting thecoupler 10, as shown in FIG. 4, by fully curling the bucket and couplerunder the excavator arm using the hydraulics of the excavator arm of theexcavator. fu that inverted position, due to the moments about thebearing hole 40, the mechanical stop 36 will rotate under the influenceof gravity so as to move its end 56 that was in engagement with thefirst latch 26 away from the first latch 26. That rotational movement isin the direction shown by the downwardly pointing arrow 58 in FIG. 4.

It should also be observed that that rotation of the mechanical stop 36does not open the front jaw 24 since the second latch 34 is stillextending partially across the opening of the jaw 24—it actually closesit further, as shown by the upwards arrow 60 in FIG. 4. Upon thatrotation of the mechanical stop, the first latch 26 is free to beretracted from its latching position into a non-latching position by thehydraulic ram 32 (not shown in FIG. 4 either, again for clarity). Thus,the rear jaw 22 can be opened (as shown in FIG. 4).

Although the basic operations of the three latches have been describedabove, the preferred method for attaching an accessory, such as a bucket62, to the coupler 10 will now be described with reference to FIGS. 3,4and 5.

Referring first to FIG. 3, the first step in the attachment procedure isthe engagement of the front jaw 24 of the coupler onto the frontattachment pin 52 of the bucket 62. That is usually done while thebucket 62 sits on the ground and is achieved by manipulation of thecoupler 10 relative to the bucket 62, while the coupler is in its normalupright orientation. However, before that can be done, the front jaw 24needs to be open, i.e. the second latch 34 needs to have been liftedinto or above the roof of the front jaw 24.

The front jaw is likely to be open if the last operation with thecoupler was the disengagement of the coupler from an accessory. However,if it is not open, to open it the second latch 34 must be lifted. That,however, can only be done while the rear jaw 22 is not accommodating anattachment pin, and only when the first latch has been driven rearwardlyto a fully extended position. That can usually be done by using thehydraulic ram 32, as shown in FIG. 3.

Once the first latch 26 is fully extended, or while it is being fullyextended, the mechanical stop 36 falls clear of the first latch 26 onceit is no longer able to reach the first latch 26 to bear against it.That additional rotation of the mechanical stop is then enough to liftthe attached second latch 34 clear of the front jaw 24, i.e. fully intoor above the roof of the front jaw 24, to open that jaw 24.

Once the front attachment pin 52 of the bucket 62 has then been engagedinto the front jaw 24 of the coupler 10, the hydraulics of the excavatorarm are then powered up to curl the bucket 62 and the coupler 10 underthe excavator, i.e. towards the cab, so as to invert the coupler 10.That positions the bucket 62 roughly above the coupler 10, as shown inFIG. 4. During that rotation of the coupler, the mechanical stop 36 willagain fall under the influence of gravity to rotate it in the directionshown by the single downward arrow 58 in FIG. 4. Thus the end 56 of themechanical stop passes the first latch 26 again.

Further, as that happens the weight of the bucket will keep the frontattachment pin securely in the cradle of the front jaw. Thus the secondlatch will be able to slide back partially across the opening of thefront jaw 24 to close the front jaw 24 for securing the front attachmentpin 52 within that front jaw 24.

While the above is happening, the first latch 26 remains fully extended.Thus it prevents the passage of the rear attachment pin 54 of the bucket62 into the rear jaw 22 of the coupler 10. However, once the above hashappened, the first latch 26 can then be retracted by the hydraulic ram32 to open the rear jaw 22—the mechanical stop 36 is moved clear of thefist latch so it will not prevent that from happening.

Next, as the first latch 26 is retracted, the rear jaw opens andeventually the rear attachment pin 54 will fall into that jaw 22 underthe weight of the bucket. Then the first latch 26 can be powered back toa latching position by the hydraulic ram. The bucket 62 and coupler 10can then be reinverted to the position or orientation of FIG. 5—thenormal working orientation—by uncurling the arrangement with theexcavator arm.

During that uncurling operation the final part of the coupling procedureoccurs—the mechanical stop falls back down into an interferenceposition, i.e. with its end 56 bearing against the first latch 26.

From the above it will be appreciated that it is important that thefront jaw is openable sufficiently by the movement/rotation of themechanical stop to allow an attachment pin to be engaged into the frontjaw, and also for it to remain sufficiently closed during normal use,i.e. while the mechanical stop is in a latching position, to preventremoval of the attachment pin from the front jaw. That balance is morereadily achieved if the latch only extends partially across the frontjaw when the mechanical stop is in its latched position. Thus the lengthof the second latch 34 is preferably chosen such that with themechanical stop in a latching position, the second latch extends onlyapproximately half way across the opening for the front jaw 24. However,adjusting the relative the lengths of the arms of the mechanical stop 36will adjust the amount of lift/movement available for the second latch34 by the rotation of the mechanical stop 36 into its fully droppedposition from its latching position. Similarly, adjusting the locationof any lower rotation stop for the mechanical stop can adjust the amountof lift/movement available for the second latch 34 by the rotation ofthe mechanical stop 36 into its fully dropped position from its latchingposition.

In this preferred embodiment the first latch 26 is a hook having anattachment pin facing surface 64 and a back surface 66. The end 56 ofthe mechanical stop 36 can bear against that back surface 66 when themechanical stop 36 is in a latching position. However, to provide a moreprecise latching position for the mechanical stop 36. The back surface66 of the first latch 26 is provided with a flange 68 having at leastone step. This stepped flange 68 provides a seat onto which themechanical stop's end 56 can sit when it is in its latching positionbehind the first latch 26. Further, if more than one step is provided,each step provides an alternative seat for the mechanical stop's end 56,whereby attachments with different pin spacings can be accommodated morereadily by the coupler 10—as shown in FIG. 3, two or even three stepsare preferably provided on the flange 68, with each step providing acorresponding latching position for the mechanical stop 36, dependingupon the amount of extension needed by the first latch 26 for itsattachment pin facing surface 64 to engage the attachment pin of therespective accessory.

Instead of multiple steps on the flange, the end 56 of the mechanicalstop could instead be stepped.

In the illustrated embodiment, the rear jaw is relatively narrow. Thusonly a narrow range of accessory pin spacings can be accommodated bythat coupler 10. However, that rear jaw 22 could be widened slightly towiden the range of accessory pin spacings accommodatable by the coupler.

The flange 68 also serves a second purpose. It provides more control forthe operation of the mechanical stop both in its latching position andbetween its latching position and it fully dropped position (i.e. foropening the front jaw). By having the flange with the step, the exactstate of rotation of the first latch will not define whether themechanical stop is in a latching position. That is because it is in alatching position whenever it bears onto the step. Thus the mechanicalstop will only fall past that latching position when the operator wantsit to do so, i.e. by fully powering forward the fist latch 26 when thereisn't an attachment pin in the rear jaw 22.

Next, with reference to FIGS. 6, 7 and 8, the removal of a bucket 62from the coupler 10 will now be described.

Referring first to FIG. 6, the first step in decoupling a bucket 62 fromthe coupler 10 is to invert the bucket 62 and coupler 10 so as to placethe bucket 62 roughly above the coupler 10. That in turn causes themechanical stop 36 to rotate clear of its latching position behind thefirst latch 26, as shown by arrow 58. The hydraulic ram 32 can then bepowered to retract the first latch 26 for opening the rear jaw 22.

Once that has been done, the bucket 62 and coupler 10 are thenreinverted to the normal orientation of FIG. 7. That in turn allows therear attachment pin 54 to swing free from the open rear jaw 22, asshown. The front attachment pin 52, however, is still secured within thefront jaw 24 by the second latch 34. Thus even if free swinging, thebucket 62 still will not detach from the coupler 10. Before that canhappen it is necessary to release the front attachment pin 52 from thatfront jaw 24.

To release the front attachment pin 52 from the front jaw 24, the bucket10 would first normally be seated onto the ground to make it safe. Thenthe hydraulic ram 32 is again powered, but this time to drive the firstlatch 26 into its fully extended position, as in FIG. 3 above, but asnow shown in FIG. 8. That in turn allows the mechanical stop 36 to fullydrop into the final bucket release position (as shown by arrow 72) inwhich it lifts the second latch 34 clear up into the roof of the frontjaw 24 (as shown by arrow 74). Only then is the front attachment pin 52also then free to be removed from the front jaw 24.

One final safety feature is incorporated into this coupler. That is theprovision of a recess 70 in the floor of the front jaw 24 (see FIG. 1).That recess, in this illustrated embodiment has a width of approximatelythe same length as the height of the jaw's opening. An attachment pincan thus locate into it. That recess 70 makes it even more unlikely thatthe front attachment pin will disengage from the front jawunintentionally. That is because even if the rear attachment pin isalready free and the front jaw is open, a free swinging bucket in thatopen front jaw will still not tend to fallout of the jaw. Instead thepin will tend to locate into the recess within that front jaw. Further,one in the recess, it will not readily come out of it due to the weightof the bucket. Thus, only when the bucket is on the ground, or shakenvigorously, will the removal of the bucket from that jaw be facilitated.That is because only then will the weight of the bucket 62 be taken offthe jaw 24 of the coupler 10. That in turn allows the coupler 10 to bemore readily manipulated in a suitable manner relative to the jaw tofree the front attachment pin 52 from the front jaw 24.

Referring finally to FIG. 9, a top plan view of the working elements ofthe preferred coupler is provided. From that view it is clearly visiblethat the second latch 34 lies between a pair of mechanical stops 36.However, other configurations within the scope of the claims as appendedhereto would be acceptable as well. The pair of mechanical stops 36, thehydraulic ram 32, the first latch 26 and the second latch 34 have eachbeen shaded with different hash lines to help identify them in thefigure.

It can also be noted from FIG. 9 that in this preferred embodiment hasthe hydraulic ram 32 sitting generally between the two mechanical stops36. That provides a more compact arrangement of the coupler 10 in itsheight dimension, whereby the bucket's digging capacity will be lesscompromised by the use of a coupler between the excavator arm and thebucket.

Referring next to FIG. 10, a further embodiment of the present inventionis shown. The coupler 110 comprises a top side 112, a bottom side 114, afront 116 and a rear 118. The coupler also comprises sideplates 120 (seeFIG. 12).

In the top side 112, two holes 122 are provided for attachment of thecoupler 110 to an excavator arm of an excavator in a conventionalmanner, i.e. with two attachment pins (not shown).

In the bottom side 114, a front jaw 124 and a rear jaw 126 are providedfor receiving two further attachment pins (not shown), this time of anaccessory (also not shown) for attachment of the accessory to thecoupler 110 again in a generally conventional manner. Indeed, for thisembodiment, a primary coupling mechanism (not shown) for that purposecan consist of a pivoting latching hook and hydraulic cylinder asdisclosed in GB2359062. However, for simplicity, those features have notbeen shown in the drawings. For completeness, however, the disclosuresof GB2359062 are incorporated herein by way of reference, and as such, afull discussion of the primary coupling mechanism is not requiredherein. The drawings do, however, show three apertures 28 that passthrough both of the sideplates 120 of the coupler 110 which are forreceiving a locking pin (through just one pair of them) for locking thelatching hook in its latched position, as disclosed in GB2359062.

The present invention, however, has an additional feature that is notdisclosed in GB2359062. That is the gravity-operated member 130, as mostclearly shown in FIG. 13. That gravity-operated member 130 is a togglein an upper wall 132 of the front jaw 124. The jaw is otherwise of agenerally conventional configuration, having a moulded lower wall (of apointed type, with a pointed front 133) and the upper wall, with theopening 131 for the jaw 124 being defined therebetween.

The toggle is mounted within a hole 134 in the upper wall 132 and ismounted for rotation about a pivot axis, as defined by a peg or bolt 136that passes through the hole 134 in a transverse direction (i.e.transverse to the sideplates 120 of the coupler 110). The head 135 andnut 137 of the bolt are shown in FIG. 12.

The toggle may pivot about the bolt 136 between an open position, asshown in FIG. 10, in which the toggle sits fully within the hole 134,and a closed position, as shown in FIGS. 11 to 13, in which part of thetoggle still sits within the hole 134, but in which a second end or nose138 of the toggle extends out of the hole 134 to partially close theopening 131 of the jaw 124.

That toggle is mounted off-centre relative to the bolt 136, whereby itis balanced so that in a normal orientation of the coupler 110, i.e. inan in-use orientation in which the front and rear jaws 124, 126 (andtherefore also any attachment pins held therein) are generally level toeach other, the toggle's centre of gravity will cause it to rotate underthe influence of gravity into that latter closed position in which thenose 138 descends into the front jaw so as to partially close theopening 131 of the front jaw 124.

By having this arrangement, in normal use an attachment pin 140 withinthat front jaw 124 will only be able to be removed from the front jaw124 through the opening 131 of the jaw 124 if the toggle was to rotateout of its way. That is because attachment pins 140 have a sizecorresponding generally to the height of the front jaw 124. However,further rotation of that toggle is not possible due to the configurationof the toggle, the bolt 136 and the hole 134. The toggle in its closedposition has a wall 148 that bears against a front wall member 142 ofthe hole 134 (see FIG. 13). Further, preferably that front wall member142, the bolt 136 and the toggle are all reinforced, toughened orhardened as well, whereby they should be able to resist even asignificant attempt to force an attachment pin 140 out of the jaw.

Referring now to FIG. 13, specific details of the preferred arrangementfor the toggle, the hole 134, the bolt 136 and the front wall member 142will now be described.

The toggle preferably comprises at its first end two perpendicular walls144, 148 that tangentially extend from a curved section 146. There isalso a third wall 149 that extends parallel to and perpendicular to thetwo other walls 144, 148, respectively. Further, that first end has anaperture therein through which the bolt 136 passes for pivotallymounting the toggle within the hole 134 of the front jaw 124. Theaperture is between the two parallel walls 148, 149 and runs parallel toall three walls 144, 148, 149.

The hole 134 in the upper wall 132 of the front jaw 124 has a flatbottom 151 and the inside surface of the front wall member 142 extendsperpendicular to that flat bottom 151. That inside surface also is flat.

The bolt 136 is arranged through the hole 134 of the first jaw 124 in aposition that is spaced from, yet parallel to, both the flat bottom 151and the inside surface of the front wall member 142. The distance of thebolt 136 from the inside surface is slightly greater than the radius ofthe curved section 146 of the toggle. The distance of the bolt 136 fromthe flat bottom is greater than its distance from the inside surface.

The aperture in the toggle is arranged concentrically to the curvedsection 146 of the toggle. As a result, the toggle will be free torotate within the hole 134 through a full 90° range of angles, i.e.between its open and closed positions. In the open position, the firstof the two perpendicular walls 144, 148 will bear against the front wall142 to provide a first rotation limitation for the toggle. In the closedposition, the second of the two perpendicular walls 144, 148 will bearagainst the front wall 142 to provide a second rotation limitation forthe toggle. Changing the angle between these two perpendicular walls144, 148 will therefore change the available range of angles of rotationfor the toggle.

In addition, the toggle comprises a second end 138—the end that extendsout of the hole 134 when the gravity-operated member 130 is in itsclosed position. That end 138 comprises a curved wall 150 that will facetowards an attachment pin 140 within the front jaw 124 when the member130 is in its closed position. That curved surface, although optional,provides an increased area of surface contact between the attachment pin140 and the toggle in the event of an attempt to remove the attachmentpin 140 from the front jaw 124 through the opening of the jaw 124 whenthe member 130 is in its closed position. As a result, forces are lessconcentrated on the toggle.

No biasing member is provided for the toggle, whereby it relies purelyupon gravity for its orientation. However, as a result it is free torotate within that 90° range if it is acted upon by an external force.Accordingly, although the toggle will prevent the withdrawal of anattachment pin 140 from the front jaw 124, the toggle will rotate toallow an attachment pin 140 to be inserted into the jaw 124 (as shown inFIG. 10).

By positioning the aperture for the bolt 136 in the first end of thetoggle, the centre of gravity of the toggle is arranged towards thesecond end of the toggle relative to its pivot axis. Thus thegravity-operated member 130, which is mounted in the upper wall 132 ofthe front jaw 124 (which upper wall 132 extends generally parallel tothe longitudinal axis of the coupler 110) will default to a closedposition whenever the coupler is level (e.g. as shown in FIG. 11).However, the toggle can be opened by rotating the coupler clockwise (asseen in the drawings) through an angle of about 90°, i.e. into the crowdposition.

Referring now to FIGS. 14, 15 and 16, an alternative embodiment of thepresent invention is disclosed in which an alternative gravity-operatedmember 130 is provided.

Instead of the coupler having a primary coupling mechanism in accordancewith GB2359062, the coupler of this embodiment features a primarycoupling mechanism involving a latching hook 154 and a blocking bar 152for that latching hook 154, similar to that disclosed in GB2330570, thedisclosures of which are incorporated herein by way of reference. Yetfurther, the front jaw is formed from two sideplates 153, rather thanhaving the moulded, pointed, configuration of the first embodiment. Bothconfigurations, however, are generally conventional and interchangeable.

In accordance with this alternative embodiment, the gravity-operatedmember 130 features a flap member that has a first pivot axis 136 thatextends in a generally longitudinal direction of the coupler 110.Therefore, to allow it to rotate out of the opening of the jaw 124 fromits locked position (as shown in FIG. 14), the coupler 110 needs to beinverted to a greater degree than the first embodiment—it must be almostcompletely inverted in order for gravity to cause it to rotate about itspivot axis into its open position. Additionally, however, the flapmember has a second pivot axis 156—a hinge axis. That second pivot axis156 can be free swinging between a straight and folded position or itmay be spring biased to keep it closed even when the coupler isinverted. The hinge, however, will have a rotation stop (not shown) asknown in the art of hinges, to prevent it from swinging in the oppositedirection to that shown in FIG. 15, whereby an attachment pin can beinserted into the jaw, but by means of which the attachment pin cannotbe removed from the jaw without inverting the coupler. Thus the hingedflap can also provide a similar function to the toggle of the firstembodiment.

Referring now to FIGS. 17 to 32, another embodiment of the presentinvention is shown. In many ways this is similar to the embodimentdisclosed in FIGS. 1 to 9. Thus similar or corresponding features ofthis embodiment to that earlier embodiment have been given the samereference signs.

This further coupler design also has a pivoting latching hook 26 that isadapted for rotation about a pivot 28 for locking an attachment pin 54in a rear jaw 22 of the coupler 10. That pivoting latching hook 26 isalso power operated under the control of a hydraulic ram 32.

The hydraulic ram 32 is attached at the free end of its piston to thelatching hook 26 at a first pivot axis 29. The free end of the cylinderof that hydraulic ram 32 is attached to the frame 38 of the coupler 10at a second pivot axis. That second pivot axis is centred on the bearinghole 40 of the mechanical stop 36. Thus a single axle 41 can be providedfor both the cylinder of the hydraulic ram 32 and the mechanical stop36.

As shown in FIG. 17, that axle 41 extends through both sidewalls of theframe 38 of the coupler 10.

The pivoting latching hook 26 has also again got an attachment pinfacing surface 64 which engages against a rear attachment pin 54 when anaccessory is coupled to the coupler 10.

The pivoting latching hook 26 also again has a back surface 66 againstwhich an end 56 of the mechanical stop 36 bears when it is in a latchingposition behind (or “in front of” when referring to its relativeposition in relation to the coupler as a whole) that hook 26. That isclearly shown in FIG. 18.

The back surface 66 of the pivoting latching hook 26 also again featuresa flange 68 that also serves to support the mechanical stop 36 forpreventing the mechanical stop 36 from swinging into a front-jaw openingposition while an attachment pin is retained within the rear jaw 22 bythe latching hook 26.

As for the second latch 34, however, although it is similarly positionedfor at least partially closing the mouth of the front jaw 24, itsinteraction with the mechanical stop 36 is different—in this embodiment,the second latch 34 is not connected to the mechanical stop 36, althoughthe two elements can selectively engage each other under certainconditions. Instead it is mounted for pivotal movement about its ownseparate pivot axle 243, much like the gravity operated member of FIGS.10 to 16.

The interaction between the pivoting latching hook 26, the mechanicalstop 36 and the second latch 34 will be further described below.

With reference to FIGS. 19 to 23, a preferred method of coupling anaccessory to the coupler 10 will now be described.

As can be seen, the aim is to achieve the completed attachment as shownin FIG. 19, i.e. with the two attachment pins 52, 54 of an accessory(not shown) safely secured within the two jaws 22, 24 of the coupler10—the rear attachment pin 54 is held by the pivoting latching hook 26in the rear jaw 22, thus also preventing movement of the frontattachment pin 52 within the front jaw 24, but with the front jaw 24also at least partially closed by the second latch 34 so that the frontattachment pin 52 would not be free to exit the front jaw 24 in theevent of an incorrect mounting of the rear attachment pin 54 within therear jaw 22 by the pivoting latching hook 26.

To achieve that completed attachment, the first step, with an uncoupledcoupler 10, is to power the hydraulic ram 32 to a fully extended state,for fully extending the pivoting latching hook 26 rearwardly across therear jaw for closing that rear jaw. See FIG. 20. By powering thatlatching hook 26 rearward, the flange 68 extending from the back surface66 of the latching hook 26 clears away from of the end 56 of themechanical stop 36. Then, with the coupler in a normal, non-invertedorientation, i.e. preferably with the two jaws at approximately the sameheight with respect to each other, the mechanical stop 36 will fall pastthat flange into a fully rotated position—the third or predeterminednon-latching position, whereat further rotation is prevented by a stop245 provided on the frame or main body 38 of the coupler 10. This stop245 is illustrated schematically in FIG. 20 and is likely to be someintegral component of the base of the frame 38 of the coupler 10.

With the mechanical stop 36 in that predetermined non-latching position,the opposite end 247 of it—extending away from the pivot axle 41 in adifferent direction—will have lifted to move a flange 249 of it clear ofa corresponding flange 251 on the second latch 34. The second latch istherefore then free to rotate between a closed or locked condition intoa non-closed position.

The interrelation between those flanges, and the rotation of the secondlatch 34 between a closed or locked condition and the non-closedposition will be described in greater detail below.

Since the second latch 34 is now free to rotate through its full rangeof motion within the frame 38 of the coupler 10, a front attachment pin52 can be slotted through the mouth of the front jaw 24 as shown in FIG.20. During that process, the front attachment pin 52 will rotate thesecond latch 34 up into the roof of the jaw 24 so that it can pass thatsecond latch 34 for locating into the rear of that jaw 24. The secondlatch will then fall again under the influence of gravity into a closedposition, thereby locking that attachment pin within that jaw 24. Thattherefore is a first safety feature of the present invention—theaccessory cannot now accidentally decouple itself from that front jaw24.

The accessory, however, is only presently half coupled to the coupler10. Thus it is now necessary to have the rear attachment pin 54 securedinto the rear jaw. For that, as shown in FIG. 21, and by the arrow 253in FIG. 20, the coupler 10 and accessory, with it two attachment pins52, 54, is rotated by crowding the excavator arm so as to place theaccessory generally above the coupler 10.

During that rotation, if the front attachment pin 52 was not alreadyfully engaged into the rear of the front jaw 22, the weight of theaccessory will pull the front attachment pin 52 tightly into the rear ofthe front jaw 22. Further, the weight of the accessory will causes therear pin 54 of the accessory to bear against the underside (or now topside since the coupler is inverted) of the pivoting latching hook 26.Yet further, due to the inversion of the coupler, and the arrangement ofthe moment of inertia of the mechanical stop 36, that mechanical stop 36will also rotate under the influence of gravity (in a counter-rotationdirection relative to the rotation of the coupler) so as to fall into anon-latching position away from the back surface 66 of the pivotinglatching hook 26.

As the mechanical stop rotates in that manner relative to the coupler, abearing surface 255 on its flange 249 (at its opposite end of themechanical stop) then engages a bearing surface 257 on the adjacentflange 251 of the second latch 34 for biasing that second latch 34 intoits jaw-closing position, thus again ensuring a secure initial couplingof the first attachment pin 52 to the coupler 10. Thus, even thoughstill only one attachment pin is within a jaw of the coupler 10 (thefront jaw 24), the accessory would still not fall out of the front jaw22 even if the coupler was to be further rotated, despite it beinginverted, due to the second latch now being biased into its closedposition.

Whilst in that inverted condition, the next step is to power thehydraulic ram to draw back the pivoting latching hook 26 into aretracted, jaw-open position, as shown in FIG. 22. This has to be donewhile the coupler 10 is inverted in order not to have the mechanicalstop 36 blocking its path.

As a result of the retraction of the pivoting latching hook 26, the rearattachment pin 54 will fall into the rear jaw 22 under the weight of theaccessory.

Once the rear attachment pin is located in that rear jaw 22, thehydraulic ram 32 is again powered to extend the pivoting latching hook26 back across the rear jaw 22 for securing the pin 54 within the rearjaw 22.

The coupler 10 can then be rotated back to a non inverted condition byuncrowding the excavator arm, as shown by arrow 259 in FIG. 22.

Once normally oriented, the mechanical stop 36 falls back into alatching position on the flange 68 (or on one of the stepped surfacesprovided on the back surface of the hook 26 if a narrower pin spacing isprovided for the accessory), as shown in FIG. 23. The accessory is thusnow correctly coupled to the coupler 10.

Referring next to FIGS. 24 and 25, further details of the second latch,and its interaction with the mechanical stop 36, will be described.

As shown in FIG. 24, the coupler 10, with an attached accessory, hasbeen rotated to an angle of approximately 45° relative to the levelorientation. The mechanical stop 36 is still in its blocking positionbehind the latching hook 26. Further, the two attachment pins 52, 54 aresecurely locked within the jaws 22, 24 of the coupler 10. Yet further,due to the orientation of the coupler, the second latch 34 has rotatedunder its own weight into a non fully closed position.

Referring then to FIG. 25, which is an enlarged view of the second latch34 and the mechanical stop 36, while the coupler 10 is still rotated toan angle of approximately 45° relative to the level orientation, it canbe seen that the second latch 34 has a pivot axle 243, about which itrotated into the illustrated non fully closed position. Further it has afirst flange 261 extending in a first direction away from that axle 243.That flange 261 serves to at least partially close the front jaw 24 whenthe second latch 34 is in a closed position (such as this non fullyclosed position, or the fully closed position of FIG. 23). Yet furtherthe second latch 34 has a second flange 251. That flange 251 is theflange mentioned above that has the bearing surface 257 that engageswith the bearing surface 255 of the mechanical stop when the coupler 10has been inverted into a crowd position. There is also a third flange285 which will be described in greater detail below with reference toFIGS. 31 to 33.

It should be appreciated that the mechanical stop 36 is in a blockingposition. Thus its end 56 bears down on the flange 68 of the pivotinglatching hook 26 (not shown in FIG. 25—see instead FIG. 24). As aresult, rotation of the mechanical stop 36 in a further anti-clockwisedirection (as viewed in FIG. 25) is not possible. As a result of that,the mechanical stop, in this blocking position serves two purposes.Firstly it serves to prevent retraction of the pivoting latching hook 26from its latched position, as per the prior art. Secondly, however, itserves to prevent rotation of the second latch into a non jaw closingposition in the roof of the front jaw 24. That is achieved s follows:

The bearing surface 257 on the second flange 251 of the second latch 34bears against the point 263 of the flange 249 on the mechanical stop 36prior to the second latch 34 achieving a position in which the frontattachment pin 52 can exit the front jaw 24. Attempts to further rotatethe second latch will also be in vain due to the inability for themechanical stop to rotate further anti-clockwise due to it alreadybearing against the flange 68 of the pivoting latching hook (asdiscussed above). Thus this arrangement provides a highly securecoupling of an accessory onto the coupler in that neither jaw can beopened while the coupler is in a normal orientation.

It should also be appreciated that with narrower pin spacings, themechanical stop would be rotated even less anti-clockwise due to itsitting on one of the stepped surfaces on the back surface 66 of thehook 26. Thus the degree of available rotation for the second latch 34from a fully closed condition would be even more restricted.

In view of the above arrangement, a special procedure needs to befollowed for decoupling an accessory from the coupler 10 of thisembodiment. This procedure will now be described with reference to FIGS.26 to 30.

The first action to taken is to rotate the coupler, and the accessory,into the crowd position, as shown in FIG. 26 for inverting the coupler.The mechanical stop 36 will then falls away from behind the back surface66 of the hook 26 (and the second latch 34 will also be biased into thefully closed position as discussed above). This position is shown inFIG. 26.

Once in that position, the rear jaw 22 can then be opened by poweringthe pivoting latching hook 26 into a retracted position as shown in FIG.27. That then unlocks the rear attachment pin 54 from its containmentwithin the rear jaw 22.

To then remove the rear attachment pin 54 from the now open rear jaw 22,the coupler 10 and accessory are once again rotated from the crowdposition and the accessory is then rested on the floor so as to allowthe coupler 10 and the accessory to be rotate relative to one anotherabout the front attachment pin 52 within the front jaw 24 as theexcavator arm is further operated.

That relative rotation (see the arrow 265 in FIG. 28) then draws therear attachment pin 54 clear of the rear jaw 22, as shown in FIG. 28.

Once the rear attachment pin 54 is clear of the rear jaw 22, and whilethe accessory is resting on the floor (in the case of a bucket, in atipped condition), the pivoting latching hook 26 can then again bepowered into a fully extended condition across the mouth of the rear jaw22, as shown in FIG. 29, for moving the flange 68 clear of themechanical stop. The mechanical stop is then free to assume the third orpredetermined position for releasing the second latch 34—in that thirdor predetermined position, the point 263 of the flange 249 of themechanical stop 36 is displaced sufficiently far away from the flange251 of the second latch 34 that they won't engage one another. Thus thecoupler can then be further manipulated by the excavator arm to orientthe coupler nearly on end so as to fully open the front jaw 24—see FIG.30. The accessory can then be released from the coupler 10 by loweringthe coupler with respect to the front attachment pin of the accessory.The accessory will then fall to its rest position on the ground,decoupled from the coupler 10.

To facilitate that final decoupling, the first flange 261 of the secondlatch 34 has a ramped nib 267 on its end, whereby even if the firstflange 261 of the second latch 34 is not fully oriented into the roof ofthe front jaw 24 by the rotation of the coupler 10, the passing of theattachment pin 52 out of the front jaw 24 against the nib 267 will pushthe second latch into that fully open position.

A beneficial result of this decoupling procedure can also be seen inthat the coupler 10 is immediately ready for coupling to anotheraccessory—the pivoting latching hook is already in its fully extendedcondition.

Referring finally to FIGS. 31 to 33, further details of the second latch34 and its interaction with the frame 38 of the coupler 10 will bedescribed in further detail.

As previously described, the second latch 34 is mounted onto the framevia a pivot axle 243. For that purpose, the frame 38 has two coaxialthrough-holes 269 in side walls 275 of a rail 277. Further, those holescan be aligned with a through-hole 271 in the second latch 34, and theaxle 243 is then threaded through those three holes. The holes are shownin FIGS. 32 and 33.

Once the axle 243 has been threaded through those through-holes 269,271, one or more cotter pin 273, or the like, is used to retain thatpivot axle 243 within the frame 38 and the second latch 38.

The second latch 34 is thus pivotally mounted to the frame 38 via a rail277 that is integrally formed on the front 16 of the frame 38 of thecoupler 10.

The rail 277 has an inside surface that is adapted to be born against bythe front of the first flange 261 of the second latch 34. Preferablythat front is a front-most surface 279 on the leading face of the firstflange 261 when the second latch is in a fully closed condition.

The front 279 is preferably planar but may instead be curved. Preferablythe inside surface 281 of the rail 277 has a corresponding shape toprovide a large surface area of contact between the second latch 34 andthat rail 277 when the second latch is in its fully forward or fullyclosed position.

As also shown in FIG. 33 (in which the second latch 34 and the pivotaxle 243 have been removed for clarity), a further load bearing surface283 is formed on the frame 38 of the coupler 10. This additional loadbearing surface 283 is spaced from the inside surface 281 of the rail277 but is again integrally formed with the frame 38.

It should be noted that the rail and the load bearing surface may bewelded to, or otherwise connected to, the frame 38.

The additional load bearing surface 283 is also for bearing any loadcarried by the frame when the second latch 34 is in a fully closedcondition, further to spread the load. For that purpose, the thirdflange 285 (mentioned above) is provided on the second latch 34.

That third flange is clearly shown in FIG. 32, in which the frame hasinstead been removed for clarity.

That third flange 285 has a bearing surface 287 on its underside. It ispositioned so that it bears against the additional load bearing surface283 whenever the front of the second latch is bearing against the insidesurface of the rail. It this provides the additional surface areaagainst which the second latch can bear when it is in its fully closedposition.

The additional area is particularly beneficial since it spreads theloading on the frame in the event of the second latch being tasked tocarry the weight of an accessory on it, such as due to a failure of someother component of the coupler (such failure releasing the attachmentpin in the rear jaw 22), or in the event of an improper mounting statefor the accessory. Simply loading such a potential force onto the railmight overload the rail.

Preferably the two bearing surfaces 287 (on the first and third flanges285 of the second latch 34 are planar and substantially perpendicular toone another.

In this embodiment it is also shown that the third flange 285 extendsonly part way across the width of the second latch (i.e. in the axledirection). It stops clear of the arm of the mechanical stop. Further,where it ends, the second flange 251 starts. In this manner, themechanical stop will not interfere with the operation of the thirdflange.

The third flange is in a different plane to the second flange of thesecond latch 34.

It is also observed that the front of the second latch 34 has twoadditional surfaces—the ramped nib 267 described above and anintermediate ramp 289. Those two additional surfaces may be blended toform a curve, which curve may be blended with the front planar surface279. Those surfaces allow or assist the above described camming of thesecond latch 34 into the roof of the jaw 24 as the front attachment pin52 exits the jaw 24 during the last stage of the decoupling procedure.

Various aspects of the present invention have been described abovepurely by way of example. It should be noted, however, thatmodifications in detail can been made within the scope of the inventionas defined in the claims appended hereto, and elements of one aspectmight be combined with elements of the other aspects, as would beappreciated by a skilled person.

The invention claimed is:
 1. A coupler for coupling an excavator bucketto an excavator arm of an excavator, the excavator bucket comprising twoattachment pins for use in the coupling, the coupler comprising: a firstside for attaching the coupler to an excavator arm of an excavator; anda second side onto which, in use, the excavator bucket would be coupled;wherein: the second side comprises a first jaw for receiving a first ofthe attachment pins of the excavator bucket for connecting the excavatorbucket to the coupler by the engagement of the first jaw with that firstattachment pin; the first jaw further comprises a toggle having a firststate—a jaw-open or jaw-unlocked state, and a second state—a jaw-closedor jaw-locked state, the toggle at least partially closing the first jawof the coupler when it is in its second state; the coupler has a secondjaw, the second jaw being for a second of the attachment pins of theexcavator bucket; the second jaw has a hydraulically or mechanicallydriven latching hook or latching plate, which, together with the firstjaw, provides a primary coupling mechanism for coupling the excavatorbucket to the coupler in a fixed orientation relative to the coupler;the toggle is a pivotal member having rotation limits defined by one ormore pivot stops; a first pivot stop is an inside surface of a frontwall member of a hole provided in a upper wall of the first jaw, thetoggle being mounted for rotation within that hole about a pivot axisthat runs in a transverse direction of the coupler, the pivoting of thetoggle moving the toggle between its first and second states; and thetoggle having two walls that extend from a curved portion, at least oneof the two walls being arranged to bear against that inside surface whenthe toggle is in the second state.
 2. The coupler of claim 1, wherein ina first orientation of the coupler, the toggle will fall, or will havefallen, under the influence of gravity into the second state, but uponreorienting the coupler to an alternative orientation, the toggle willfall, or will have fallen, under the influence of gravity from thatsecond state into the first state.
 3. The coupler of claim 1, wherein inthe second state, the first jaw's opening is partially closed by thetoggle.
 4. The coupler of claim 1, wherein in the second state, thefirst jaw's opening is fully closed by the toggle.
 5. The coupler ofclaim 1, wherein in the normal, in-use orientation, an attachment pincan still be inserted into the first jaw by virtue of the toggle beingfree to move in a direction for allowing that insertion, but the togglenot allowing an attachment pin to be removed from the jaw past themember.
 6. The coupler of claim 1, wherein the coupler comprises a framehaving two sideplates, extending generally between the top and bottomsides of the coupler.
 7. The coupler of claim 1, wherein the toggle isfitted to a front jaw of the coupler, which jaw points in a generallylongitudinal direction of the coupler.
 8. The coupler of claim 1,wherein the first jaw has no hydraulically or mechanically drivenlatching hook or latching plate.
 9. The coupler of claim 1, wherein thetoggle provides a secondary securing mechanism for securing an accessoryto the coupler, the toggle not serving to couple an accessory to thecoupler in a fixed orientation relative to the coupler, but insteadmerely serving to attach or tether the accessory to the coupler simplyby retaining an attachment pin of the accessory within the first jaw ofthe coupler when the toggle is in its second state.
 10. The coupler ofclaim 1, wherein the toggle has a biasing member for assisting inensuring that the toggle adopts the second state when the coupler is inits normal, in-use orientation, but which biasing force will be overcomeby gravity by the weight of at least an element of the toggle forputting the toggle into its first state when the coupler is at leastpartially inverted to a sufficient degree.
 11. The coupler of claim 1,wherein the toggle, when in its first state, fits within the holeprovided in the upper wall of the first jaw, and part of the toggleextends out of the hole when the toggle is in its second state.
 12. Thecoupler of claim 1, wherein the two walls of the toggle areperpendicular to each other.
 13. The coupler of claim 1, wherein thehole in the upper wall of the first jaw has a flat bottom and the insidesurface of the front wall member extends perpendicular to that flatbottom.
 14. The coupler of claim 1, wherein the distance of the pivotaxis for the toggle from the inside surface of the front wall member isgreater than the radius of the curved portion.
 15. The coupler of claim1, wherein the toggle rotates through 90° when moving from the firststate to the second state.
 16. The coupler of claim 1, wherein the twowalls of the toggle are at a first end of the toggle, and the two wallsare perpendicular walls that tangentially extend from the curvedportion.
 17. The coupler of claim 1, wherein an end of the toggle thatat least partially closes the first jaw of the coupler when the toggleis in its second state comprises a curved wall that will face towards anattachment pin within the first jaw when the toggle is in its secondstate.
 18. An excavator comprising a coupler according to claim
 1. 19. Acoupler for coupling an excavator bucket to an excavator arm of anexcavator, the excavator bucket comprising two attachment pins for usein the coupling, the coupler comprising: a first side for attaching thecoupler to an excavator arm of an excavator; and a second side ontowhich, in use, the excavator bucket would be coupled; wherein: thesecond side comprises a first jaw for receiving a first of theattachment pins of the excavator bucket for connecting the excavatorbucket to the coupler by the engagement of the first jaw with that firstattachment pin; the first jaw further comprises a toggle having a firststate—a jaw-open or jaw-unlocked state, and a second state—a jaw-closedor jaw-locked state, the toggle at least partially closing the first jawof the coupler when it is in its second state; the coupler has a secondjaw, the second jaw being for a second of the attachment pins of theexcavator bucket; the second jaw has a hydraulically or mechanicallydriven latching hook or latching plate, which, together with the firstjaw, provides a primary coupling mechanism for coupling the excavatorbucket to the coupler in a fixed orientation relative to the coupler;the toggle is a pivotal member having rotation limits defined by one ormore pivot stops, the toggle being mounted to the coupler about a pivotaxis, the pivoting of the toggle moving the toggle between its first andsecond states; the first jaw is a front jaw of the coupler; the toggleprovides a secondary securing mechanism for securing an accessory to thecoupler; a first pivot stop is an inside surface of a front wall memberof a hole provided in a upper wall of the first jaw, the toggle beingmounted within that hole; and the toggle having two walls that extendfrom a curved portion, a first of those two walls being arranged to bearagainst the inside surface of the front wall member when the toggle isat a relevant allowable extreme of rotation therefor.
 20. An excavatorcomprising a coupler according to claim 19.